A typical modular conveyor belt is disclosed in U.S. Pat. No. 3,870,141 issued to J. M. Lapeyre on Mar. 11, 1975. According to this patent identical modules formed by injection molding are pivotally connected to one another to form a conveyor belt of a desired length and width. Each module includes a plurality of elongated elements, each of which has a first pivot end and a second pivot end. The plurality of elongated elements are connected together such that apertures defined in each of the first and second pivot ends lie along a first and second pivot axis respectively, which pivot axis are parallel one to the other. The pivot ends of one module are intermeshed and pivotally connected by means of a pivot rod with the pivot ends of another module until an entire belt having a desired length and width is formed. Plastic belts built according to the teachings of this invention have been well received by industry and have many particular uses. The module itself is typically injection molded out of plastic by means of a simple two-piece mold which includes two "halves". One "half" typically molds the bottom portion of the module and the other "half" typically molds the top portion.
U.S. Pat. No. 4,051,949 issued on Oct. 4, 1977 also to Mr. Lapeyre is an improvement patent over the 3,870,141 patent and provides raised ribs which cooperate to form channels suitable for receiving a transfer comb such that articles can readily be introduced and/or removed from the conveyor belt. U.S. Pat. No. 4,171,045 issued on Oct. 16, 1979 also to J. M. Lapeyre recognize the need for including a conveyor surface which would not allow objects riding on the conveyor surface to slip and thereby allow the belt to pass underneath. The belt disclosed and formed by the teachings of the 4,171,045 patent is similar to that of the 3,870,141 and 4,051,949 patents discussed heretofore except that selected ones of the raised ribs include "dogs" which extend above the normal portion of the conveying surface to contact and push articles on the conveying surface such that the belt will not slip underneath.
In a similar manner, U.S. Pat. No. 4,213,527 issued Jun. 22, 1980 to Lapeyre, et al, further discloses a module for forming a link conveyor belt which has ridges or flight members extending transverse to the direction of travel for preventing the conveyor belt from slipping under articles riding on the conveyor surface. A study of this patent, discloses that the particular modules are molded by an extrusion process and then the spaces between link ends are cut into place. Similarly, U.S. Pat. No. 4,170,281 issued on Oct. 9, 1979 and U.S. Pat. No. 4,080,842 issued on Mar. 28, 1978 both to Lapeyre, also show conveying belts having members extending transverse to the conveying surface for moving articles on the conveying surface along the belt such that the belt cannot slip underneath the article.
U.S. Pat. No. 4,159,763 issued on Jul. 3, 1979 and assigned to the same assignee as the previously discussed patents is also an improvement patent over the basic 3,870,141 patent. The conveyor belt taught by this patent is U.S.D.A. approved as it allows for easier inspection and cleaning of the pivot pins and link ends, and has somewhat more open area and consequently more air flow through the belt.
Still other modular link conveyor belt patent applications by Lapeyre and/or owned by the same assignee as the present invention which might be considered relevant to the present invention include: Ser. No. 483,210 entitled "LINK CHAIN BELT" filed Apr. 14, 1983; Ser. No. 179,523 entitled "MODULAR CENTER DRIVE CONVEYOR BELT" filed Aug. 19, 1980; and Ser. No. 457,482 entitled "LIGHTWEIGHT MODULAR CONVEYOR BELT" filed Jan. 12, 1983. In addition patent applications entitled "CONVEYOR BELT HAVING INSERTABLE AND SELECTABLE CONVEYING MEMBERS", "CONVEYOR BELT HAVING A HIGH FRICTION CONVEYING SURFACE", and "END-TO-END MOLDED CONVEYOR BELT MODULE" having serial numbers 642,534; 642,533; and 642,535 respectively, also disclose subject matter having some similarity to the present application.
Although it is believed that the injection molded plastic belting discussed above is the most relevant prior art known to applicant, a conveyor belt disclosed in a U.S. patent issued to V. C. King on Nov. 28, 1933 and having number 1,936,764 has some visual similarity to the present invention and might be considered relevant. However, even a cursory review of this prior patent reveal significant differences from the claimed invention. In addition British patent 1,127,316 dated Aug. 4, 1968 discloses a wire conveyor belt with very heavy cross rods. This British patent, although showing a belt having large amounts of open area, clearly is not even as relevant to the present invention as the other patents and patent applications discussed above.
It is therefore an object of the present invention to provide a simple and inexpensive modular conveyor belt which is exceptionally light weight, and which accurately tracks along its path of travel.